feat(mail): 增强邮件认证与审计能力

- 新增邮件认证结果解析、存储与前端展示，支持查看 SPF、DKIM、DMARC 及原始头信息。
- 扩展邮件规则条件，支持抄送、附件、大小、日期及嵌套条件组合。
- 增加邮箱容量统计与发送前配额校验，超限时返回明确错误。
- 新增管理端发送审计页面与接口，支持按邮箱、事件、Message-ID 和时间筛选。

apps/web/src/pages/mail.tsx

@@ -1963,6 +1963,7 @@ function MessageMetaPanel({ message, availableLabels, onAddLabel, onRemoveLabel,
           <MessageMetaRow label="接收时间">
             <span>{formatDateTime(message.receivedAt)}</span>
           </MessageMetaRow>
+          <AuthenticationResultRow message={message} />
           {availableLabels && onAddLabel && onRemoveLabel && (
             <MessageMetaRow label="标签">
               <div className="flex flex-wrap items-center gap-1.5">
@@ -2024,6 +2025,41 @@ function MessageMetaPanel({ message, availableLabels, onAddLabel, onRemoveLabel,
   )
 }
 
+function AuthenticationResultRow({ message }: { message: MailMessage }) {
+  const auth = message.authentication || { authenticationResults: "", receivedSpf: "", spf: "unknown", dkim: "unknown", dmarc: "unknown" }
+  const title = [auth.authenticationResults, auth.receivedSpf].filter(Boolean).join("\n\n")
+  return (
+    <MessageMetaRow label="Auth">
+      <div className="flex flex-wrap gap-1.5" title={title || undefined}>
+        <AuthStatusBadge label="SPF" value={auth.spf} />
+        <AuthStatusBadge label="DKIM" value={auth.dkim} />
+        <AuthStatusBadge label="DMARC" value={auth.dmarc} />
+      </div>
+    </MessageMetaRow>
+  )
+}
+
+function AuthStatusBadge({ label, value }: { label: string; value?: string }) {
+  const status = normalizeAuthStatus(value)
+  return (
+    <Badge variant="outline" className={cn("rounded-md font-mono text-[11px] font-normal", authStatusClassName(status))}>
+      {label}:{status}
+    </Badge>
+  )
+}
+
+function normalizeAuthStatus(value?: string) {
+  const status = (value || "").trim().toLowerCase()
+  if (["pass", "fail", "softfail", "neutral", "temperror", "permerror", "none"].includes(status)) return status
+  return "unknown"
+}
+
+function authStatusClassName(status: string) {
+  if (status === "pass") return "border-emerald-300 bg-emerald-50 text-emerald-700"
+  if (["fail", "softfail", "permerror"].includes(status)) return "border-red-300 bg-red-50 text-red-700"
+  return "border-slate-300 bg-slate-50 text-slate-600"
+}
+
 function MessageMetaRow({ label, children }: { label: string; children: React.ReactNode }) {
   return (
     <div className="grid gap-1 sm:grid-cols-[5rem_minmax(0,1fr)]">